• Question: Is there an edge to space?

    Asked by Nucleolus (Ben Sheridan) to Alice, Bose, Christian, Emma, Steve on 16 Mar 2016. This question was also asked by albielog.
    • Photo: Steve Marsden

      Steve Marsden answered on 16 Mar 2016:

      Well, yes and no.

      As far as we know, the universe is infinite and has no edge (Dude, no edge!)

      However, the universe isn’t infinitely old, and the speed of light is very slow, compared with the size of a galaxy, never mind compared to an infinite universe! Because of this, we can only see a small ball of the universe centred on the Earth. Anything outside of this ball is too far away, and light hasn’t had enough time to reach us yet. This ball is called the observable universe and does have an edge. That edge is constantly retreating from us as more light makes its way to Earth.

    • Photo: Benjamin Bose

      Benjamin Bose answered on 17 Mar 2016:

      So when we say universe, we usually mean observable universe, i.e. the part of the universe we can see. Beyond that, there is uncertainty. The entire universe is probably infinite as Steve said, but could be even smaller (yes smaller!) than the observable one.

      To imagine it being smaller, imagine the universe being round like Earth (but much smaller than Earth) and you looking at something far away could just be an image of something much closer to you.

      Outside the entire universe, well there are theories which say our universe is actually just a piece of a higher dimensional reality, and like ants on a wire we can only move forward or backwards but never off the wire into this new dimension.

      Outside higher dimensions? Well, that’s pushing further into the realm of imagination and is one of the best things about science -tying in your imagination with reality through experiment 🙂

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